A next-generation multimedia wireless communication system, into which extensive research is ongoing, is required to process various types of information such as image data and radio data at high data transmission rate, beyond initial voice-oriented services.
Recently, attention has been paid to Orthogonal Frequency Division Multiplexing (OFDM) capable of processing data at high transmission rate. OFDM refers to a multi-carrier modulation scheme in which a frequency band is split into a plurality of orthogonal subcarriers to transmit data. OFDM can attenuate inter-symbol interference with low complexity. In OFDM, serially input data symbols are converted into N parallel data symbols and the converted parallel data symbols are transmitted in the N split subcarriers.
Subcarriers maintain orthogonality in the frequency domain. Each orthogonal channel experiences independent frequency selective fading and inter-symbol interference can be minimized because the interval between transmitted symbols is increased. Orthogonal Frequency Division Multiple Access (OFDMA) refers to a multiple access scheme for achieving multiple access by independently providing a part of available subcarriers to each user in a system using OFDM as a modulation scheme. OFDMA provides each user with frequency resources called subcarriers. Respective frequency resources are independently provided to a plurality of users so that frequency resources do not overlap in general. Consequently, the frequency resources are exclusively allocated to users. In an OFDMA system, frequency diversity for multiple users can be obtained through frequency selective scheduling and subcarriers can be allocated in various forms according to a permutation scheme for subcarriers.
When a User Equipment (UE) transmits an uplink (UL) signal to an eNode B (eNB) in some wireless communication systems, a UL control channel on which control signals are transmitted can be physically distinguished from a UL data channel on which data is transmitted and a plurality of control/data channels may be simultaneously transmitted using one symbol. The transmit powers of UL transport channels (or transmission channels) may be determined through a specific equation.
Meanwhile, a maximum transmittable power that can be allocated for UL transmission by the UE is determined according to bandwidth allocated to the UE, processing performance of the UE, battery performance of the UE, and the like. Accordingly, if the total sum of transmission powers necessary for simultaneously transmitting a plurality of transport channels exceeds the maximum transmittable power, proper UL transmission cannot be performed.
Accordingly, there is needed a method for effectively allocating powers to a plurality of UL transport channels transmitted simultaneously using different physical regions.